Some articles mention that anonymous sources specifically take note of the speech patterns of other people so they can use those to throw off the trail. I'd be very surprised if the author didn't at least try to do that, or agree to have the NYT rewrite each sentence while preserving the meaning.
It's an interesting exercise and can and might be able to rule out some authors, but it seems like someone harboring such opinions and wishing to express them to some extent (and has with others -- in the resistance) will be discovered in short order.
Outing this person might be an even bigger story than the OpEd itself. But I put my money on old fashion journalism rather than text analysis.
If I were the author I would take my own essay and then run it through algorithms like this and massage my word choices to match other people.